Carbon nanotubes, including single-walled carbon nanotubes (SWNTs) have been the subject of research since the discovery of carbon nanotubes. Carbon nanotubes possess unique properties such as diameters of about 0.7 to about 500 nanometers (nm) and aspect ratios of about 5 to about 10,000. They are also electrically conducting, which makes them valuable as molecular electrical wires in applications directed to molecular electronics, nanoelectronic components, and field emission displays. Carbon nanotubes may be either multi-walled (MWNT) (e.g., comprising 2 or more concentric layers) or single-walled. Depending on their atomic structure, single wall carbon nanotubes may have either metallic or semiconducting properties, and these properties, in combination with their small dimensions makes them particularly attractive for use in the fabrication of nano-devices. In particular, research is being directed to using single wall carbon nanotubes in field effect transistors.
While carbon nanotubes display a number of advantageous properties, they also possess properties that render it difficult to use them in electronic applications. For example, single wall carbon nanotubes tend to rope as a result of Van der Waal's forces between individual nanotubes. In addition, because of their high aspect ratios, carbon nanotubes tend to agglomerate into bundles that make the dispersion and placement of nanotubes at specific desired locations difficult.
In general, the noncovalent adsorption of carbon nanotubes to organic and inorganic surfaces has been controlled by modulating the interactions between the entire surface of the nanotube and the desired substrate. For example, carbon nanotubes have been aligned on substrates by flowing gas over a droplet of carbon nanotube suspension. However, despite their potential utility, methods of orienting carbon nanotubes between discrete points, features, or across a series of features on a substrate remain elusive.
It is therefore desirable to develop methods by which carbon nanotubes can be oriented between discrete points or features on a substrate.